L1B Change of Location- Amendment possible

USA L1, L2 Visa
1

Dear Team,

I am currently on L1 Blanket visa. My petition is filed against the city X, CA. However I work from client location in City B, IL. Is it possible to work legally from a different location other than petition city and state? If yes, what is the procedure employer need to follow. Is there any amendement which can be applied to petitions.
2

i have valid L1B blanket visa till ( 2022). currently I am in india.

Note : Still i have not yet travelled

Bleow are the question

Amendment really required if we are changing the location and Cleint . ?

I- 129 has my old location address.?

Also do i need to go for stamping again(My visa is valid till 2022).

Please suggest